Method of and apparatus for making a sheet metal zig-zag key

ABSTRACT

This invention describes a method of making a sheet metal zig-zag key for a lock. The technique of making a zig-zag key, either as a duplicate of another or in the original form, consists of passing a heavy current through the key so as to get it into a plastic state such as, for example, a red heat, and then deforming it into the desired shape.

BACKGROUND OF THE INVENTION

Keys for locks are normally made by stamping or grinding a blank to thecorrect shape. This, however, is impractical for the duplication of athin sheet-metal key by a retail store.

This invention has, as one object, the provision of an improved methodof making a key from a blank of sheet spring metal.

Another object of the invention is the provision of low-cost, efficient,quick, method of making a key from a blank of thin sheet spring metal.

SUMMARY OF THE INVENTION

According to the invention, a thin blank of spring metal is electricallyheated to a plastic condition and then deformed to the desired shape.The extent of the deformation may be controlled by having spacers, andpressure-operated shaping device, for positioning the blank to conformto the shape of a duplicate key held in a position adjacent said blank.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of method and apparatus for making a key inaccordance with the invention.

FIG. 2 shows a portion of the apparatus in FIG. 1 in an inoperativeposition.

FIG. 3 is a detail view of a portion of the apparatus.

DETAILED DESCRIPTION OF THE DRAWINGS

In FIG. 1, I show one method of manufacturing such a duplicate. The key2 that is to be copied is mounted on a moving platform 4 on a framewhich is not shown. This moving platform 4 can be pushed to the left bya cam-and-lever 6. Against this key 2 are moved steel or ceramicelements 8, 10, 12, 14 and 16 which are then clamped by a plate withknurled screws 20 and 22. This setting of the elements 8 to 16 is donewhen the plate 4 is to the right as shown in FIG. 2. At this point oftime in the process the blank 30, springs 42, 44, 46, 48 and 50, andkey-forming elements 32, 34, 36, 38 and 40 are in the position shown inFIG. 3. Moreover, at this point in the process, the virgin or blank key30 has not yet been formed. Against this key 30 the rather stiff springs42, 44, 46, 48 and 50 press on the key-forming elements 32 to 40.

The electric current to heat the new key 30 is supplied by a lowvoltage, high current transformer 60. When it is necessary to shape thekey 30, a switch 62 is closed, passing heavy current through the key 30.The blank or virgin key 30 has its ends connected to the terminals 64and 66 to the secondary of the transformer by clamps 68 and 70. When thecurrent passes through the thin section of the new key 30, the key stripbecomes as hot as desired for the forming operation. The lever 6 isswung clockwise, forcing the movable pre-set elements 8 to 16 to pressagainst the blank 30 and form it into the desired shape. The opposingspring driven elements 32 to 40 press the key strip into tight contactwith the elements 8 to 16.

Because the current can actually be shut off just before the key isshaped, the elements that press the key can be made of conducting metal,such as steel, but this is not necessary. Either each element can bemade of a non-conductor, such as ceramic, or merely the tips of theelements pressing the key 30 can be made of such material. Thus, theelements 8 to 16 can be made of steel, and thus be mechanically ruggedwhile the contacting points can be made non-conducting.

If desired, the switch 62 can be interlocked with the lever 6 so thatthe whole operation is done with a single motion. Normally, one wouldlike to start the electric current slightly ahead of the pressure butthis is not absolutely necessary, since the pressure can be applied tothe key 30 while the current is passing. This particular detail of themechanism would depend on the thickness of the steel, the magnitude ofcurrent passed, and the particular details of the design. I show asimple embodiment of the invention; other embodiments can, of course, beconstructed.

If the key is to be curved in a transverse direction to its length, asshown in my co-pending patent Application Ser. No. 770,484, filed oneven date herewith and entitled PICKPROOF LOCK, the elements that formthe key, of course, should be curved accordingly.

The strip from which the key is made will, of course, be shortened inover-all length as the key is formed and, therefore, the contact 64should be made so that it can move a short distance toward the contact66 as the key is formed, or the contact should not be so tight as toprevent the metal of the key from sliding through the contact as the keyis formed. The handle position of the key, however, has to be heldtightly so that the curves in the key are correctly related relative tothe handle. This would be for the normal design of the lock and key butnot necessarily the only one. The key can be referenced to the forwardend, if desired, in which case the clamp 64 should be held very tightlyin position, and clamp 66 should be free to move toward it. This dependsstrictly on the design of the lock and I would normally prefer to keepthe handle as the reference for the key.

When an original key is to be made, the options for forming it are many.The key can simply be stamped by rigid dies common to the sheet-metalindustry. A device similar to that shown in FIG. 1 can be designed wherethe elements 8 to 16 are set not by another key but by a set of cams orother mechanisms so as to produce a very wide variety of keys. Alocksmith can even set the elements 8 to 16 by hand to create acompletely new key, if he so desires.

A first key 2 is mounted upon platform 4 and rigidly affixed to theplatform at both its forward and rearward ends by elements 74 that aresecured to the platform. The steel or ceramic elements 8, 10, 12, 14,and 16 are slid along grooves on the underside of member 18 until theirright-hand ends respectively touch the key 2 at which point bolts 20 and22 are tightened to rigidly secure the steel or ceramic elements 8, 10,12, 14, and 16 in their proper places so that they cannot move withrespect to the platform 4. It is further apparent that they will movewith platform 4.

The handle end of the blank 30 is mounted between supports 66 and 76,the latter of which is movable into key clamping position by rotatingthe knurled screw head 77 which causes screw 78 to move through fixedsupport 70 to press element 76 into the handle of the blank 30. Theforward end of the blank 30 is mounted between supports 64 and 65. Thesupport 64 is movable toward the support 65 in the same way that support76 was movable toward support 66; that is, a knurled nut 79 may berotated to cause screw 80 to move to the left through stationary support68, pressing element 64 toward element 65 to clamp the forward end ofthe blank.

The left ends of the springs 42, 44, 46, 48 and 50 are all fixed inposition as shown in FIG. 3. Thus, when handle 6 is rotated from theposition shown in FIG. 2 to the position shown in FIG. 1, the platform 4moves to the left and presses the different portions of the blank 30different distances in accordance with the position of the left-handends of the steel or ceramic elements 8, 10, 12, 14, and 16. This ispreferably done, however, only after switch 62 has been closed so thatstep-down transformer 60 passes a very large current through the blank30, heating it to a plastic state. After the blank has been formed tothe correct shape as aforesaid, the switch 62 is opened, the blank 30 isallowed to cool and thus be set, whereupon the handle 6 is rotated tothe position of FIG. 2 and the blank 30, which is now a duplicate key,is removed and is ready for use. It is, of course, possible to removethe blank 30 after it has been formed to the correct shape but before itis cooled and to temper it in any suitable way which is appropriate fortempering material devices of the character described.

I claim to have invented:
 1. The method of making a key of the type thatis used to open a lock, from a blank, that comprises a strip of metal,comprising:heating said blank, to a plastic state, and converting saidblank into a key of the type used to open a lock comprising deformingsaid blank from a flat plane to give the blank curvature and providedisplaced areas at given locations along its length, to give desireddisplacement to tumblers by said areas.
 2. Apparatus for making a blankinto a second key that conforms to a first key, said keys being in theform of strips, comprisingmeans for mounting the first key and the blankwith faces of the first key and the blank in a generally parallel andspaced relationship, heating means for heating the blank, to a plasticstate, and blank-shaping means, including a series of spaced key-shapingdevices located between the first key and the blank, for pressing theblank into the shape of said first key.
 3. Apparatus as defined in claim2 in which said heating means comprises means for passing an electriccurrent through said blank to heat the same to a plastic state. 4.Apparatus as defined in claim 2 in which said blank shaping meansincludes means for moving the blank toward the first key and includingmeans whereby such motion presses the blank against said series of keyshaping devices to form the blank into said second key having the shapeof the first key.
 5. Apparatus as defined in claim 4 in which said"means for mounting the first key and the blank" comprises means forholding the blank at its opposite ends.
 6. The method of using a key, ofthe type that is used to open a lock and which is of the type that is astrip with depressions in its side wall at each of a plurality of givenlocations, to make a duplicate key from a blank, comprising:placing theblank in parallel relation with said key, heating said blank to aplastic state, providing a plurality of spacers, with one spacer foreach given location respectively with all of said spacers being of thesame length; and positioning one end of each such spacer in contact withits complementary given location and the other end of the spacer incontact with the blank. deforming said blank to conform the heated blankto a configuration which touches said other ends of said spacers, andallowing the blank to cool and become rigid in said configuration toform a key of the type that is used to open a lock.
 7. The method ofmaking a key as defined in claim 6 in which said heating step is carriedout by passing an electric current through said blank.
 8. The method ofmaking a key from a blank as defined in claim 6 whichcomprises:supporting said key, of the desired shape, at both ends, saiddeforming step comprising pressing said blank into said spacers at eachone of said given locations.
 9. The method of claim 1 in which saidblank is supported only at both of its ends during the deformingstep,holding a key of the desired shape adjacent to said blank duringthe deforming step, and effecting the deforming of said blank bypressing a forming device against the blank to provide said depressedareas at positions along the blank complementary to depressed areas ofsaid "key of the desired shape," including using said "key of thedesired shape" to position the forming device during the deforming step.